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[dm-devel] Re: Patch to lsi rda device handler



Yanqing_Liu Dell com wrote:
Hello,

Here is the lsi rdac device handler code that was posted:

https://www.redhat.com/archives/dm-devel/2008-May/msg00003.html

The following patch is to address a NULL pointer problem in lsi rdac
device handler.

In function get_rdac_req, after a request is successfully allocated, the
area that the cmd pointer points to should be zeroed out. However, the
function zeros out the command pointer itself, along with some other
adjacent area. This results in NULL pointer dereference when submitting
inquiry commands when checking virtual disk ownership during device
discovery time. The kernel trace is attached at the end of the message.

The change is to zero out the area that the cmd pointer points to,
instead of the pointer itself in the allocated request structure.

--- scsi_dh_rdac.c.orig	2008-07-17 01:53:10.000000000 -0400
+++ scsi_dh_rdac.c	2008-07-17 01:45:28.000000000 -0400
@@ -214,7 +214,7 @@
 		return NULL;
 	}
- memset(&rq->cmd, 0, BLK_MAX_CDB);
+	memset(rq->cmd, 0, BLK_MAX_CDB);
 	rq->sense = h->sense;
 	memset(rq->sense, 0, SCSI_SENSE_BUFFERSIZE);
 	rq->sense_len = 0;

Nice catch. Thanks. I guess we need to buy a book on programming in C :) Not sure how scsi_dh_hp_sw did it right, but the others goofed and we did not catch it.

You should send your writeup and patch to the linux-scsi list, so that it can be included in the next batch of patches for 2.6.27. You should also fix up scsi_dh_emc.c. Send it all in one big patch.


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